The brainstem contains a number of central mechanisms regulating a number of vital physiological functions. Disorders in the regulation of the cardio-pulmonary system can result in a number of pathological conditions some of which may be potentially life threatening.
People suffering from sleep apnoea have cardio-pulmonary disorders manifesting with breathing irregularities and even frequent stops of breathing (apnoea), particularly during sleep, but also during the day. The apnoeic episodes during the daytime are less dangerous, because they can be self-managed by conscious actions, apnoeas during the night are more dangerous. Patients can feel very sick in everyday life, due to oxygen deprivation. During episodes of apnoea, blood pressure can collapse and subsequently the heart may stop its function, resulting in inadequate brain perfusion, loss of consciousness and even sudden death. At least 4% of the adult population in developed countries suffers from sleep apnoea.
There are several types of apnoea. One type, central apnoea, involves a dysfunction of the respiratory muscles (including the diaphragm) for lack of command from the respiratory centre in the brainstem. This is the type occurring in approximately 10 percent of the cases. Another type, obstructive apnoea, occurs in 80% of cases, when in spite of respiratory movements there is no supply of air to the lungs, due to collapse of the upper airways. The third type, a mixed apnoea, occurs in the rest of the patients.
It is known, that apnoea can be counteracted by stimulation of the patient in various ways. In infants shaking is usually enough to arouse the baby from sleep and restart the process of automatic breathing and even provoke gasps, which induces resuscitation from asphyxia. Adults suffering from sleep apnoea now sleep with a mask, tightly connected to the facial contours, so a slight over-pressure of air from a device can continuously be applied (Continuous Positive Airway Pressure—CPAP). This keeps the airways open and allows air supply by spontaneous breathing. In any case these patients have to sleep attached to their breathing apparatus, limiting their freedom of movement during sleep. For patients with sleep apnoea travelling means carrying the breathing apparatus with them. For patients suffering from central sleep apnoea or mixed type sleep apnoea, treatment with CPAP is showing limited success. Modulating the air pressure (BIPAP) offers only a slightly better success rate.
Research in cats has shown that breathing can be stopped by inhalation of anoxic mixtures for over 1 minute, with subsequently a severe drop in blood pressure and heart rate. Mechanical or electrical stimulation of the nasopharynx can induce a sniff- and gasp-like “aspiration reflex” (Tomori and Widdicombe, 1969, Be{hacek over (n)}a{hacek over (c)}ka & Tomori, 1995, Tomori et al. 1995, 1998, 2000). Due to resuscitation effects, the blood pressure returns to normal, heart rhythm normalizes, respiration and neuro-behavioral functions return to normal. The anesthetized cat seems to be in good condition, even after as long as three minutes without adequate blood pressure, heart rate and breathing. This experiment can be repeated over 10 times on the same cat, without any noticeable negative consequences.
Provocation of such an aspiration reflex has been indicated as a possible means for interruption of apnoea in cats (Tomori et al., 1991, 1995, Be{hacek over (n)}a{hacek over (c)}ka & Tomori, 1995, Jakus et al., 2004). Alternatively, similar resuscitation may be induced by (electro)-acupuncture, (electro)-acupressure or mechanical stimulation of the nasal philtre in cats, inducing spasmodic inspiration (Be{hacek over (n)}a{hacek over (c)}ka & Tomori, 1997).
International Patent Application No. PCT/NL2006/000599, which has not been published prior to the priority date of the present invention, describes the surprising discovery that a resuscitating stimulation of the brainstem with an induced aspiration reflex in order to obtain resuscitating physiological effects also works in human beings. That document also describes some devices designed for treating apnoea and related cardio-respiratory syndromes in humans via activation of the respiratory centre of the brainstem followed by an induced aspiration reflex.
International Patent Application No. PCT/NL2006/000599 describes an ear stimulator in general terms.
International Publication No. WO2007/147046 discloses an apparatus that can be worn by a user. The apparatus comprises a first portion that can be worn on, behind or in the ear and a second portion that can be attached under a human nose. The second portion comprises a detector to sense a breathing signal of the user. The first portion comprises a stimulation device which is designed to provide a stimulus to the human's acoustic nerve inside the ear when the device detects a disturbance in the respiratory cycle of the user, e.g., caused by sleep apnoea.
International Publication No. WO00/66215 discloses an apparatus comprising a sensor and a stimulation device both connected to a control unit. The control unit is arranged to determine whether or not a user is suffering from a respiratory disorder, such as sleep apnoea, in dependence on signals received from the sensor and to control the stimulation device such as to stimulate nerves in the labyrinth of a human ear to counteract the disorder.
Wang Xiao-hong, et al., Chinese Journal of Integrated Traditional and Western Medicine, October 2003, p. 747-749, disclose some observations on the effect of aurical acupoint pressing in treating sleep apnoea. They report that in the night after acupoint pressure had been applied people showed an improved apnoea-hypopnoea index. They do not disclose any apparatus or method to counteract apnoea at a time it occurs.